US1156549A - Elastic-fluid turbine. - Google Patents

Description

E. C. PERRY, JR.

ELASTlC FLUID TURBINE.

APPLICATION FILED APR.9.1914.

1,156,549. Patented Oct.12,1915.

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Inventor,-

Edward Gl w b EDWARD c. PERRY, an, or- WEST LYNN, MAssAoHUsn'rrs, ASSIGNOR rro GENERAL ELECTRIC COMPANY,'A CORPORATION'OF NEW YORK.

nnnsrxomrorn TURBINE.

Specificationof Letters Patent.

Patented Oct. 12, 1915;

Application filed April 9, 1914. Serial 1\To. 83(), 805.

To, aZZw/wm it may concern p Be it known that I, Enwann C. Pnrin'nJn, a citizen of the United States, residing at West Lynn, county of'EsseX, State of Massachusetts, have invented certainnewand use ful Improvements in Elastic Fluid Turbines, of which the following is a specification. 1 I

The present invention relates to steam turbines and particularly to a turblne dea signed to operate without the provision of any of the usual forms of speed governor or emergency shut-01f means. Steam may be supplied to such turbines at anearly constant pressure, as through a suitable'reducing valve, and so long as the load remains substantially Constant the speed will not vary to any considerable extent. Moreover, the turbine wheel may be so designedthat the rotation losswill be highvascompared I with the shaft output and in this way the speed may be controlled for varying loads. Inan arrangement of this character, if, due to the failure of the reducing valve for example, the bowl pressure should rise considerably the steam flow to. the turbine wheel would increase and might cause an undesirable increase in the speed of the bucket wheel, particularly if it should occur at a time of relatively light load; According to the present invention I aim to provide an arrangement for taking care of such anvemergency condition and one wherein, even ifthebowl pressure should risevery high, the speed of the turbine wheel will not become unduly high; 4 i 1 ,As is known, the power obtainedfrom steam furnished at a given pressure depends directly uponthe exhaust pressure, that is the power depends upon the diff rence in pressurebetween the inlet and eX- haust. In carrying out my inven'tionlmake nozzle area. This outlet area will preferably besuch that with normalbowl pressure the steain .dischargedfrom the turbine wheel can pass from the wheel chamber wlth sufiicient rapidity to keep the pressure thereinat a value desired for normal operatlon. Ifnow an increase 1n bowl pressure occurs which would ordinarily increase the; speed of the wheel, the increased quantity of steam tanner escape through the exhaust opening until the pressure in the Wheel chamber builds up to a higher value. The. effect of this building up of ,pressure is to niaintain'the available energy and hence the steam velocity at, a practically constant value. The increased flowof steamhas, of course, the effect of somewhat increasing the speed of the wheel, but this tendency to, increase is offset in a substantial measure by the rotation losses of the wheel revolv ing in a denser medium, said losses inf creasing very rapidly with increasing speed. Turbines of this type are in general adapt ed forvery small units and are of practical utility only in those caseg'whe e extreme simplicity of greater importance than economy in operation. c

In addition to the above arrangement-,1 may also cause the steam discharged from the turbine wheel casing toimpinge against vanes carried by the turbine shaft. vanes will be oppositely disposed tothe buckets of the turbine "so 'thatthe steam in pinging against them will produce a re, tarding effect. This retarding effect will increasewith'both the speed of rot tion and with the velocity of the. steam fiowingifrom theturbine wheel casing, and as this velocity increaseswith increase in the turbine (casing pressure, itwill be clear that the rotating vanesjwill function at the proper time to help maintain constant s 'aee'd. I Referring to the drawings, Figure 1 isa section through a turbine illustratingpan embodiment of my invention; 2 a side view lookingtoward the left fof Fig.1 and with parts broken away Fig. 3 his a sectional view showing a "modification, and Fig. l is'a detail development illustiating the arrangement of Fig. i i I Referring first to Figs. 1 and 2, 5 is shaft mounted in suitable bearings "(not These shown) and carrying the'turbine wheel 6. This turbine wheel will preferably be purposely designed to have a large rotation loss as compared to the shaft output, and to this end the diameter may be made large as compared to the nozzle area and shaft output, or the buckets may be made unusuallyhigh, or both. 7 is the turbine wheel casing having the removable closure 8 in which is arranged the nozzle 9 for directing motive fluid to the turbine wheel. Motive fluid is supplied to the nozzle by pipe 10 in which is arranged a suitable reducing valve 11, which will be set to reduce the motive fluid pressure down to the desired value. 12 is the exhaust conduit. Between the turbine wheel and theexhaust conduit is arranged suitable means for restricting the outflow from the casing. In the present instance I have shown the opening between the casing and exhaust as being closed by a plate 13 in which are arranged openings 14. The combined area of these openings bears a definite relation to the nozzle area and will be such that with normal pressure at the nozzle entrance the steam can flow from the casing with suflicient rapidity to keep the pressure in the casing and surrounding the wheel at a normal desired value. As is well known, the quantity of steam flowing through an orifice depends upon the difference in pressure upon the two sides thereof, and with normal initial pressure, the openings 14 will preferably be of such area as to require but a small pressure difference. Should the pressure at the nozzle entrance increase,

as for example by failure of the reducing valve, then, as will be obvious, a much larger amount of steam will tend to flow. This increased amount cannot flow from the opening 14 at the pressure normally existing on the two sides thereof, and as a consequence the pressure of the wheel chamber will immediately build up. The effect of this building up of pressure is to maintain the avail able energy and hence the steam velocity at a practically constant value. The increased flow of steam still has the effect of somewhat increasing the speed of the wheel, but this tendency is offset in a substantial measure by the increased rotation losses of the wheel due to its revolving in a denser medium. The result will be to limit the speed of the turbine.

The arrangement shown in Figs. 3 and 4 is the same as that shown in Figs. 1 and 2,

except that in addition thereto I provide an impeller wheel 15 having its vanes 16 arranged reversely to the buckets of the turbine wheel, as most clearly seen from Fig. 4. I have applied the same reference numerals to the corresponding parts in Figs. 3 and .4 asare used in Figs. .1 and 2. The retarding efiect of this impeller wheel will increase with increase in speed and also with increase in the velocity of flow from the openings 14. From this it will be clear that in case the initial pressure on the nozzle should increase, thereby increasing thepressure in the turbine wheel casing, as already explained, an increased velocity offlow from the openings 14 will result. This'increased flow will cooperate with the impeller wheel in preventing rise in speed.

In accordance with the provisions of the patent statutes,'I have described the principle of operation of my invention, together with the apparatus which I now consider to represent the best embodiment thereof; but I desire to have it understood that the apparatus shown is only illustrative, and

that the invention can be carried out by other means.

What I claim as new and desire to secure by Letters Patent of the United States, is,

1. The combination in a turbine, of a casing, a bucket wheel therein, a nozzle for supplying motive fluid to the wheel, an exhaust conduit, and means forming a restricted passage for conveying motive fluid from the casing to the conduit, which pas- .ingwill be slightly above that outside the same.

3. The combination in a turbine, of a casing, a bucket wheel therein, a nozzle for supplying motive fluid to the wheel, and an exhaust conduit, said casing having a series of openings therethrough forming a restricted passage for motive fluid from the casing to the exhaust conduit said openings being of such area and bearing such relation to the nozzle area that with normal admission pressure the pressure in the casing is above that outside the same.

4. The combination in a turbine, of a casing, a shaft, a bucket wheel carried by the shaft Within'the casing, a nozzle for supplying motive fluid to the wheel, said casing having a restricted exhaust opening the area of which bears a definite relation to the nozzle area, and an impeller wheel mounted on said shaft outside the casing and adjacent the exhaust opening, said impeller wheel having its vanes reversely arranged to the buckets of the turbine wheel.

5. The combination in a turbine, of 2. casthe casing, means for supplying motive Wheel being reversely arranged to the buck I fluid to the Wheel, an exhaust c0nduit,,said ets of the turbine Wheel. casing having a series of openings therethrough forming a restricted passage for motive fluid from the casingto the exhaust conduit, and an impeller Wheel mounted on said shaft outside the casing and adjacent said openings, the vanes of said impeller my hand this sixth day of April, 1914.

EDWARD C. PERRY, JR. l/Vitnesses:

JOHN A. MCMANUS, J12, GEORGE W; PENTHENY.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

' Washington, D. C.

1O In Witness whereof, I have vhereunto set

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